For some applications, it is desirable to plasma treat a container. For example, plasma treatment is useful for medicinal inhalation devices, including pressurized inhalers such as metered dose pressurized inhalers (MDIs) and dry powder inhalers (DPIs), which are widely used for delivering medicaments. The relatively high surface energy of materials typically used as containers for medicinal inhalation devices (e.g., deep drawn stainless steels or aluminum) can cause medicament particles in suspension formulations, for example, to adhere irreversibly to or adsorb onto the interior surface of the container. Such adhesion or adsorption can lead to a loss of potency and/or erratic dosing during the shelf-life of the device. Interaction between a container and a medicinal formulation can also potentially lead to enhanced medicament degradation or corrosion of the container.
While plasma treatment methods are known for modifying the surface properties of various articles, plasma treatment of containers continues to provide challenges.